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Author Topic: Soldering Help  (Read 8925 times)
W9KDX
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Posts: 771




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« on: February 18, 2012, 08:34:41 AM »

I am having some difficulty getting the hang of soldering coax to PL-259s.  I am using LMR cable and the PL-259 inserts.  I think I have the center wire OK; when I have to redo a cable that part always looks good and I have no issues with melting anything.  I think the issue is the wire braid and getting it to solder to the PL-259 outer connection. 

I am using a 25 watt iron and I get the feeling I need more heat, or possibly I need to keep the iron on the joint a lot longer; when I do, it seems to help.  Also, when I screw in the spacer, it always seems to twist the braid.

Any suggestions would be appreciated.  I am not getting any shorts in the line, I check it with a tester.  I seem to just not get the braid to bond.

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Sam
W9KDX
W8JX
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« Reply #1 on: February 18, 2012, 08:41:43 AM »

Any suggestions would be appreciated.  I am not getting any shorts in the line, I check it with a tester.  I seem to just not get the braid to bond.

You need a lot more than 25 watts here. 60 to 75 watts with a tip with some thermal mass is pretty much minimum here. The more heat energy you have the quicker you can heat and flow solder while minimizing total time cable is exposed to heat. I use a 140/250 watt dual heat gun for this myself.
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K8AXW
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« Reply #2 on: February 18, 2012, 08:56:35 AM »

PLD:  I feel your pain!  JX is right on the money.... get a 140/250 watt soldering gun.  You can use a larger soldering IRON if you grind the tip down to fit in the groove where you see the soldering holes in the connector.  But a soldering gun tip fits perfect and is the way to go. It is also less awkward because it is shorter and easier to control. 

Putting the cable in a vise to hold it helps immeasurably. Rotate it as necessary to get to the holes.

Now, this embarrasses me to admit this but it took me 35 or 40 years to find out the best and fastest way to solder the braid (through the holes in the connector) is to first take a rattail file and file off the nickle plating in the groove with the soldering holes.

This exposes the brass which gives a much better heat transfer and lets the solder flow much faster.  This also results in less heat damage to the center insulator.
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KD8GEH
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« Reply #3 on: February 18, 2012, 09:19:56 AM »

Welcome to coax connectors 101 HA!  I know some OM's that still have trouble with them. The trick is having a hot enough gun (or iron) good quality solder (kester) and lots of practice.

I use a weller soldering gun and a little jig I made to hold the cable. Trick is trimming the cable correct paying attention how you fold the braid back. I use a razor blade for the center conductor and trim the braid with sharp scissors. Dont get the center pin too hot or use cheap connectors.

Heres a link to get you started: http://www.hcarc.us/articles/soldering%20PL-259%20connectors.htm

Everyone has their own method that works for them. Some use torches, others pencil irons..I've even seen them use huge old plumbing irons HA!

Anyhow, its all about what works for you personally. Always check continuity before connecting the radio. I've been doing them for 35 years and rarely have an issue.

Enjoy and have fun!

73 DE Dave KD8GEH
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WA4VBC
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« Reply #4 on: February 18, 2012, 09:42:11 AM »

I have found that an large iron (100-200 watts) will work much better on PL-259s than an gun. 
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AC5UP
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« Reply #5 on: February 18, 2012, 10:15:53 AM »

...I use an 80 watt Weller iron intended for the stained glass trade that works well on PL-259's * if * I give it plenty of warm up time, pre-tin the braid and remember to pull the iron away as soon as the solder flows.

Allowing adequate warm up gives the tip "thermal mass" (for lack of a better description) so it has plenty of reserve heat to transfer to the connector shell. Pulling the iron off as soon as the solder flows minimizes the risk of dielectric meltdown. When the braid is bonded to the shell that's all you need. Nothing to be gained by cooking the coax beyond the point of permanent continuity.

I've also heard that buying non-acid rosin to "grease" the braid after it's tinned is a good idea. Any decent grade of traditional 60/40 solder should work well, but then I remind myself all the newer stuff is lead-free so look for a low melting point. As for soldering guns, I never had much luck with them on connectors. Less thermal mass in the tip with a smaller contact point (thermal path?)............ (?)
« Last Edit: February 18, 2012, 10:39:02 AM by AC5UP » Logged

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W8JX
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« Reply #6 on: February 18, 2012, 10:18:45 AM »

I have found that an large iron (100-200 watts) will work much better on PL-259s than an gun. 

I find gun much better. More focused and easily to vary heat too.
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K7KBN
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« Reply #7 on: February 18, 2012, 10:30:41 AM »

I use the Weller iron that AC5UP mentioned.  Lowe's carries them, I believe.  The tip of mine is a perfect fit for the PL-259.  The most important consideration, as others have said, is the thermal mass: the weight (mass) of the iron's tip as compared to the mass of the connector.  Your 25 watt iron gets every bit as hot as my 80 watt iron, or even my 250 watt iron.  But put that small tip on a relatively large, cold connector and the temperature drops instantly.  With greater mass, the temperature drop is much less and recovery is much faster.

As for filing out the nickel plating on a PL-259 - that isn't required if you use silver-plated connectors. Solder just LOVES hot silver.  Hot nickel, not so much.
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73
Pat K7KBN
CWO4 USNR Ret.
KL0S
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« Reply #8 on: February 18, 2012, 11:08:38 AM »

Someone taught me a trick years ago that works well to solder coax braid to the connector....you've got to use silver connectors.

--First, put the PL-259 inner connector in a vise or holder and put a cold solder blob on top of each hole leading to the braid....it don't have to be pretty, just enough to hold the solder there.
--Prep your coax using whatever method you normally use and apply solder to the braid so that it covers the circumference at the point where you'll make the cut thru the inner foam.
--Use a sharp box cutter (or a tubing cutter works as well) to cut thru the foam down to the inner conductor; be careful not to nick the center conductor.
--Simply screw the connector down onto the coax (don't forget to put the outer barrel on first -- not that I've ever done that!) to the point that the top of the braid is against the top of the cylinder it's screwing into.
--Now, here's the magic....use your iron and heat the connector in the vicinity of the cold solder blobs....once you've transferred sufficient heat to the connector the braid will "suck" the cold solder blob down into it and make a solid connection - repeat for the other three holes.

The first time I saw this done I was amazed how easy it was and what a nice connection it made.  YMMV, but I've used this procedure ever since and never had a problem with a connector.

73 - Dino KL0S
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W8JX
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« Reply #9 on: February 18, 2012, 11:37:21 AM »

Your 25 watt iron gets every bit as hot as my 80 watt iron, or even my 250 watt iron. 

Not hardly.
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W9KDX
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« Reply #10 on: February 18, 2012, 12:25:07 PM »

Much thanks guys.  Glad to hear this is a widespread problem.  At least I don't feel so dumb.

I read a lot of problems with 80 watt and above evaporating the rosin so I ordered a 65 watt.  I needed a de-soldering iron anyway.  As soon as I get it, I'll give some of these tricks a try.  I never thought of prepping the braid on the insert first!  What a logical idea.

 
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Sam
W9KDX
W8JX
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Posts: 6692




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« Reply #11 on: February 18, 2012, 04:39:10 PM »

I read a lot of problems with 80 watt and above evaporating the rosin so I ordered a 65 watt.  

Even a 25 watt one will "de-tin" with time if left unattended and plugged in. You need to keep a wet sponge or rag to clean tip from time to time and re-tin it. I would have went with 80.
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W6EM
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« Reply #12 on: February 18, 2012, 07:07:17 PM »

....As for filing out the nickel plating on a PL-259 - that isn't required if you use silver-plated connectors. Solder just LOVES hot silver.  Hot nickel, not so much.

I guess, over the years, that the manufacturers have looked for less expensive ways to make PL-259s and SO-239s.  In my junk box, I have some old surplus ones as old as the '40s and '50s , and they are either dark gray (silver that's oxidized) appearance or have a silver colored tin covering.  The amount of brass in the PL-259s was a good deal more in the old days.  Although I haven't weighed them to compare new vs/ old, it's obvious to the feel.

Soldering the braid under the barrel has always been a challenge and has tradeoffs.  I use a 250W gun, but, as others have suggested, heat it first, then apply it to the barrel to quickly heat the barrel.  I usually do four quadrants, over each hole in the barrel.

Nickel plating doesn't wick solder well, and it will definitely take longer to do if you can get it to tin suitably.  For me, I won't buy a nickel plated connector or adaptors.  Either tin or silver plating, as I know both will flow solder quickly.

As to difficulties with solder tinning, you might try coating with non-contaminating flux from a flux pen or needle-bottle feed.  Kester 951 felt-tipped applicator pens are a couple of bucks and are very easy to use to wet the surface of the barrel with liquid flux.  You could coat the adapter and shield before putting it inside the barrel.

Good luck and happy tinning.  BTW, for those that think nickel takes solder easily, try tinning a piece of heater element wire.  Nickel/chrome alloy or nichrome as it's called.

73,

Lee
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G3RZP
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« Reply #13 on: February 19, 2012, 02:43:49 AM »

I find a paint stripping hot air gun the best. Remove the PVC or whatever jacket for 1.125 inches. With the (in my case 40 watt Wellrer), tin the braid. Cut braid to length using a pipe cutter. Cut inner insulation to length, make sure coupling sleeve is on cable right way round, fit PL259. Heat with hot air gun until solder applied through holes melts, then use Weller iron. The hot air gun is 850 watts, so it heats quickly.

Use good, silver plate, Teflon insulated 259s, none of the cheap rubbish.
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W5DQ
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« Reply #14 on: February 19, 2012, 03:03:11 AM »

I read a lot of problems with 80 watt and above evaporating the rosin so I ordered a 65 watt.  

Even a 25 watt one will "de-tin" with time if left unattended and plugged in. You need to keep a wet sponge or rag to clean tip from time to time and re-tin it. I would have went with 80.

I quit using wet sponges a while back and now use a wire bundle mass ('pillow' for a lack of a better term) that resembles a coarse, open weave, unsoaped Brillo pad. The pillow is gold in color and stuffs into a metal holder that sits on the desk next the iron. Just shove the tip in the pillow and move back and forth a couple of times, pull it out and the black oxidized crude it gone and the tip is shiny read to solder. I believe I first got these at either Digikey or Mouser when I ordered some parts a while back but have since seen them in a couple of electronics supply stores recently. The pillow seems to last forever at the rate I use it. If you solder all day long, everyday, it probably will wear out faster. They are not expensive, less than a $2-3 per if I remember correctly.

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
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